tag:blogger.com,1999:blog-1812431336777691886.post6572032106073048884..comments2024-02-29T03:57:00.088-05:00Comments on The Mermaid's Tale: The Prisoner's Dilemma dilemmaAnne Buchananhttp://www.blogger.com/profile/09212151396672651221noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-1812431336777691886.post-16477130340980158552013-07-02T22:19:50.146-04:002013-07-02T22:19:50.146-04:00The diagram is wrong, it's reversed.The diagram is wrong, it's reversed. Tutuhttps://www.blogger.com/profile/03767915173143436672noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-23687275830357844672012-05-20T10:56:13.270-04:002012-05-20T10:56:13.270-04:00Yes, we basically agree.Yes, we basically agree.Ken Weisshttps://www.blogger.com/profile/02049713123559138421noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-70510051007344031112012-05-20T09:55:29.447-04:002012-05-20T09:55:29.447-04:00I think we are probably more in agreement than not...I think we are probably more in agreement than not. <br /><br />I'm saying the following. In the Hawk-Mouse game (the original animals used by Maynard Smith and Price), or any other frequency-dependent situation, the animal doesn't make any "complex" calculations in its head (but see below). The pay-off is immediate. So envision that there are four behavioral options, two or three of which correspond to options in the Hawk-Mouse game. If they animal randomly engages in one option, which is the correct "move" given its opponent's "move" then it will gain the payoff. The animal just "behaves" and natural selection provides the payoff. <br /><br />If the animal has a simple form of memory (which need not be heritable, as you point out), it can begin to develop what we might call strategies when the games are repeated. A simple one is known as "Pavlov"--do what you did last time if you won, otherwise shift your strategy. Others, as you know, are "tit for tat"--cooperate first, then do what your opponent did last time, and another is "always defect"--never cooperate, a strategy that is an ESS in the prisoner's dilemma. <br /><br />I guess the key thing here is the idea of memory with respect to the different "moves" one can make when the PD or other games are repeated. Pavlov requires you to remember two things, what you did last time and if you won. Tit for Tat requires you to remember only what your opponent did last time. These strategies are quite robust to all other strategies played against them, and it seems that many animals, even insects, could engage in them. <br /><br />If the strategies (or just memory) are heritable, then you can get lineages of animals playing different strategies. Environmental unpredictability is certainly a challenge for game-theory but as I noted, game theory was never designed to deal with unpredictability since the game is deterministic once the strategy sets are determined. The only way around this is to assume a new ESS will invade the population quite rapidly if the environment changes. <br /><br />To me, game theory was a simple way to model the complexities of frequency-dependent selection independent of cognition, braininess, or the subtle machinations of the human mind. There are usually a very limited set of moves and with minimal assumptions (some form of memory, either hard-wired or flexible), you can get animals interacting in seemingly complex ways. The fact that it is often applied to humans only shows that humans often behave as if we are "controlled" by simple genetic-based algorithms when everyone knows that we are not.rich lawlerhttp://www.propithecus-verreauxi.comnoreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-66150775527526380712012-05-18T13:56:16.786-04:002012-05-18T13:56:16.786-04:00If I understand your second paragraph, the questio...If I understand your second paragraph, the question is whether the fitness advantage is because the brain is specifically tailored to do the particular game, or just tailored to evaluate the realities of its environment and figure their implications out.<br /><br />Unless there is evidence to the contrary that I'm unaware of (certainly a possibility), the specific behavior itself need not be heritable. <br /><br />For example, there need not be a specific gene or genotype 'for' understanding the nature and ubiquity of gravity. If you drop something, it falls, and if the brain can learn that, it need not be pre-wired for it. And there need not be a separate genotype to learn when something rests on or partly on something else and hence won't fall down.<br /><br />Someone too dense to learn these things about its environment, would get eaten by a predator or something, and be selected against, and for whatever brain-related genotypic reason might be involved, those variants would go.<br /><br />A programmable computer is a lot more versatile and hence advantageous than one like, say a digital watch, that can only do a few pre-specified things. (and here I'm not speaking of Payley's Watchmaker!)<br /><br />If we had to evolve task-specific genotypes, we'd need genes for chess and contract bridge. This goes back, in a sense, to Alfred Wallace's argument (which was Paley-like) that our ability to do calculus couldn't have evolved because our ancestors didn't do calculus, so must have been put in our brains by God.Ken Weisshttps://www.blogger.com/profile/02049713123559138421noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-84671799934032795582012-05-18T13:00:32.941-04:002012-05-18T13:00:32.941-04:00Alan Grafen made a similar point to yours and call...Alan Grafen made a similar point to yours and called it the phenotypic gambit: model the evolutionary basis for a behavior as if the simplest genetic system controlled it. <br /><br />More generally, game-theory, like kin selection, just relies on "behaving." You just behave in a particular fashion and to the extent that the behavior is beneficial (and heritable) then your behavior might be picked up by selection. No need to make complex calculations of strategies (or relatedness) in your brain. <br /><br />What game theory doesn't yet incorporate well is drift. Once the strategies are set, the "game" is entirely deterministic. Getting a particular strategy off the ground is likely going to be more due to drift than selection. Game theory assumes an immediate population response by a superior strategy, but in the real world, it's not clear that the population can respond so quickly (due to drift and demographic stochasticity).rich lawlerhttp://www.propithecus-verreauxi.comnoreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-13407468822690889902012-05-17T08:36:20.899-04:002012-05-17T08:36:20.899-04:00Wonderful example of the Prisoner's Dilemma i...Wonderful <a href="http://bengoldacre.posterous.com/magnificent-application-of-game-theory-and-ps" rel="nofollow">example </a> of the Prisoner's Dilemma in action. Game show head games.Anne Buchananhttps://www.blogger.com/profile/09212151396672651221noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-3362565896350265532012-05-17T08:11:59.605-04:002012-05-17T08:11:59.605-04:00Right. And for many species, certainly mobile ones...Right. And for many species, certainly mobile ones like us, being able to learn from unpredictable environments and situations would seem an obvious way to be 'adapted'.<br /><br />It is easier to think of a 'gene' (or some fixed set of genes) 'for' playing Prisoner's Dilemma, and a separate set for other games, than to try to imagine how all our genes could evolve to make us environment-assessors/responders. But selection working on the net result seems to have done it.<br /><br />It's just not as satisfying since it doesn't lead to a specific gene to study. Not so neat a story!<br /><br />Well, is that so? Isn't it just as neat, or even neater, that what matters is the phenotype, and learning ability is an incredibly fascinating phenotype, and one doesn't have to think about genes at all to marvel at it, and want to understand it.<br /><br />Just as we don't need to study each stone to admire the Taj Mahal.Ken Weisshttps://www.blogger.com/profile/02049713123559138421noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-15958228110496754042012-05-17T05:53:24.308-04:002012-05-17T05:53:24.308-04:00This is nice.
I'd like to add that a problem...This is nice. <br /><br />I'd like to add that a problem I have with so many behavioral strategy discussions is they lack much acknowledgement of learning and environment- that an animal can be biased toward engaging in some behaviors more than others (or at all) simply because it's what others around him do.Holly Dunsworthhttps://www.blogger.com/profile/05260104967932801186noreply@blogger.com